Sliding window

ABSTRACT

A sliding window having a frame with a slidable panel and a further panel therein, the slidable panel being mounted on pivot arms coupled to slider means such that in its closed position the slidable panel is coplanar with the further panel and pressed against compression sealing means on the frame, but on opening movement, the slidable panel moves, by means of said pivot arms, away from the sealing means and out of the plane of the further panel to lie parallel thereto, whereby it can be overlapped with the further panel.

Umtefl States Patent 11 1 1111 3,841,024

Cheng 1 Oct. 15, 1974 1 SLlDllNG WINDOW 2,680,268 6/1954 Rutherford 49/130 2,764,784 10/1956 McCall 49/130 [75] Invent Albert Chmg Kowloon 3,293,801 12/1966 Henning 49/130 Hong Kong FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee' g f' i 439,664 12 1967 Switzerland 49/130 466,466 5 1937 Great Britain 49 130 [22] Filed: Mar. 13, 1973 K h Primary Examiner ennet Downey [21] Appl' 340690 Attorney, Agent, or Firm-Fleit, Glpple & Jacobson [30] Foreign Application Priority Data ABSTRACT Mar. 24, 1972 Great Britain 14036/72 A sliding window h ing a fr me wi h a slid ble panel and a further panel therein, the slidable panel being [52] US. Cl 49/130, 49/216, 49/221 m n n piv arms ouple to slider means such [51] llnt. Cl E05d 15/20 hat in its closed position the slidable panel is coplanar [58] Field of Search 49/128, 130, 219, 225, i h th f rth r p nel n pressed against compres- 49/216-218, 221-223 sion sealing means on the frame, but on opening movement, the slidable panel moves, by means of said [56] References Cited pivot arms, away from the sealing means and out of UNITED STATES PATENTS the plane of the further panel to lie parallel thereto, 1 815 607 7/19 Beers 49/110 whereby it can be overlapped with the further panel. 2,145,403 l/l939 Nemec 49/225 11 Claims, 8 Drawing Figures Pmm nnm 1 51am SHEET 2 BF 3 FIG. 2.

III/II I l PATENT-EDEN 1 SW 13,841 x024 sum 3 or 53 illiI i Ill/ll SLIDING WINDOW The invention relates to sliding windows.

Previously proposed sliding windows have the disadvantage that they cannot be made weatherproof due to the absence of a positive compression seal. Sliding windows, however, have considerable advantages over casement windows, particularly that installation is more simple and the metal content of the frames can be reduced since no problems arise regarding sagging, thereby resulting in a reduction of cost.

According to the invention, there is provided a sliding window having at least one slidable panel movable between a closed and an open position, at least one further panel which may be fixed or slidable, a surrounding frame and means, including pivot arms, for mounting the slidable panel in the frame, said means being so arranged and disposed that the slidable panel in its closed position lies substantially in the same plane as the further panel and in abutment with compression sealing means of the frame and, when moved from its closed position to its open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that the sliding panel can be overlapped with said further panel.

Said means are preferably so constructed that the slidable panel in open positions is movable in .said further plane along a track of the frame but as the slidable panel approaches its closed position it is swung, on the pivot arms, into the plane of the further panel to bring it into abutment with said compression sealing means on the frame and compression sealing means on a mullion of the fixed panel.

The further panel is preferably normally fixed but is mounted for sliding movement, for example to facilitate cleaning.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a sectional plan view through one embodiment of a sliding window according to the invention;

FIG. 2 is a sectional elevation on line 22 of FIG. .1;

FIG. 3 is an elevation from the inside of the window of a bottom roller assembly for the window of FIG. 1;

FIG. 4 is an elevation from the inside of the window of a top guide assembly for the window of FIG. 1;

FIG. 5 is a fragmentary elevation of the portion indicated by the arrow V on FIG. 1;

FIG. 6 is a fragmentary plan view of the portion indi cated by the arrow VI on FIG. 2;

FIG. 7 is a fragmentary plan view corresponding to the lefthand end of FIG. 1 and showing a modified embodiment of a sliding window according to the invention; and

FIG. 8 is a schematic sectional elevation corresponding to FIG. 7.

In the following description, inner" is to be interpreted in the sense of towards the interior face of a wall in an aperture in which a window is provided and outer is to be interpreted as towards the exterior face of such a wall.

Referring to FIGS. 1 to 6 of the drawings, a sliding window has a fixed surrounding frame 1 comprising vertical side members 2 and 3, a lower member 4 and an upper member 5. The frame 1 can be secured in an aperture in a surrounding wall, for example by dove-tail arrangements generally indicated at 6.

A fixed panel 7 and a slidable panel 8 are mounted in the frame 1, each of the panels 7 and 8 having a frame comprising opposite vertical jambs l0 and 11, an upper member 12 and a lower member 13.

The lower member 4 of the surrounding frame is formed to present an inner track 14 and an outer track 15. The lower members 13 of the frames of the slidable panels 7 and 8 mount rollers 16 which bear on the inner track 14. The lower member 13 of the slidable panel 8 is pivotably coupled to one end of each of the two link arms 17, the other end of each of the link arms being pivotally coupled to a respective roller housing 18.

The roller housings 18 each include a roller 19 bearing on the outer track 15, the two roller housings 18 being coupled together by tie bars 20. The link arms 17 are pivotally connected by rivets 21 to a bracket 22 secured to the lower member 13 of the panel 8 and the linkarms 17 are pivotally connected to a respective one of the roller housings 18 by rivets 23, the lower member 13 of the panel 8, the link arms 17 and the tie bars 20 forming a parallelogram arrangement as is apparent from FIG. 1.

The upper member 5 of the surrounding frame 1 has an outer track 24 on which a pair of nylon guides 25 are suspended. The guides 25 are coupled to the upper member 12 of the slidable panel 8 by link arms 26. The link arms 26 are connected by rivets 27 to the respective guide 25 and by rivets 28 to brackets 29 secured to the upper member 12 to give a parallelogram arrangement of similar proportions to thatprovided at the lower part of the slidable panel 8.

By means of the two parallelogram arrangements the slidable panel 8 is is movable between a closed position, inwhich it lies in the same vertical plane as the fixed panel 7, and open positions, in which it lies in a plane parallel to the plane in which the fixed panel 7 lies and located outwardly thereof, whereby it can be overlapped with the fixed panel 7 to leave opening.

The members 2, 3, 4 and 5 of the surrounding frame 1 have flanges 30 thereon and resilient sealing strip 31 is provided on outwardly facing edges of the flanges 30. By pressing the fixed panel 7 and the slidable panel 8 inwardly against the resilient sealing strip 31, the panels 7 and 8 can be sealed against draughts.

In operation, with the slidable panel 8 in an open position, that is to say overlapped with the fixed panel 7, the slidable panel 8 is moved leftwardly as viewed in FIG. 1 to close the window, by a force applied to a handle 9 on the side member 10 of the panel 8, the rollers 19 moving along the outer track 15. As the panel 8 approaches the vertical member 2 of the frame 1, the lefthand roller housing 18 moves into abutment with a fixed nylon stop 32 and thelefthand guide 25 into abutment with a fixed nylon stop 33. Further movement of the panel 8 leftwardly will cause it to pivot inwardly on the rivets 21, 23 of the link arms 17 and the rivets 27, 28 of the link arms 26, to move substantially into the same plane as that in which the fixed panel 7 lies. The vertical member 10 of the panel 8 engages an angled face 34 of a stop 35 on the side member 2 of the frame 1, which angled face 34 guides the member 10 inwardly to press it against the adjacent sealing strip 31. The fixed nylon stop 32 in addition to restricting lateral movement of the roller housing 18 also helps to clamp a window down the roller housing 18 by means of a wedging action as can be seen from FIG. 3.

The side member 10 of the fixed panel 7 forms a mullion and mounts a crescent-shaped locking catch 36 which is engageable with a keeper 37 on the side member 11 of the slidable panel 8. Actuation of the locking catch 36 moves the slidable panel 8 leftwardly to cause the side member 10 thereof to move further along the angled face 34 of the stop 35 and pulls the side member 11 of the slidable panel 8 inwardly to press it against a sealing strip 38 on the mullion and to press a sealing strip 39 on the side member 11 of the slidable panel 8 against the mullion.

The window is thus closed, locked and sealed.

It is to be noted that when, during closing of the window, the two link arms 17 move off the roller housings 18, the loading of the entire slidable panel 8 is transferred onto the inner track 14 thus preventing a torque being exerted on the two free resting roller housings 18.

To open the window the locking catch 36 is released and a force is applied to the slidable panel 8 to slide it rightwardly as viewed in FIG. 1. The mullion formed by the side member 10 of the fixed panel 7 includes a nylon block with an outer face 40 which is angled and which causes the whole slidable panel 8' initially to move outwardly, due to the parallelogram arrangement of the link arms 17 and 26. The outer ends of the link arms 17 have portions 42 which project outwardly beyond the rivets 23 and which, in the closed position of the slidable panel 8, are engaged behind stops 43 provided on a flange 44 of the lower member 4 of the frame 1. The stops 43 prevent the roller assemblies 18 moving rightwardly until the link arms 17 have pivoted about the rivets 23 until they are substantially aligned with the tie bars 20. When the link arms 17, and also the link arms 26, are so aligned the slidable panel 8 has moved to a position sufficiently outwardly of the plane of the fixed panel 7 to be moved rightwardly to overlap the panel 7.

In the fully closed position of the slidable panel 8, the portions 42 of the link arms 17 bear against the flange 44 of the lower member 4 of the frame 1 and exert additional inward pressure on the lower member 13 of the slidable panel 8 to press it more firmly against the sealing strip 31. A similar arrangement is'provided at the upper edge of the slidable panel 8 by end portions of the link arms 26 bearing on a flange of the upper member of the frame 1.

The purpose of initially restricting lateral movement of the roller housings 18 is to make sure that the side member 11 of the panel 8 has cleared the mullion before the entire slidable panel 8 is slid further to the right. To prevent the slidable panel from being excessively pushed outwardly, thus causing mis-alignment, adjustable nylon stops 45 (FIG. 5) are fixed to the top and bottom of the side members and 11 of the slidable panel 8 and cooperate with the flange 44 of the lower member 4 of the frame 1 and the corresponding flange on the upper member 5 of the frame 1. The height of the stops 45 can be adjusted to permit the slidable panel to be moved outwardly for cleaning.

Although the panel 7 has been referred to as fixed it is desirable that it be movable to facilitate cleaning, but providing it to be movable requires means to apply an inward force theretoin the closed position to maintain the seal provided by the sealing strip 31.

In the closed position of the panel 7 the side member 11 thereof is pressed against the sealing strip 31 by an angled face 46 of a stop 47 similar to the stop 35. The side member 10 of the panel 7, which forms the mullion, is pressed inwardly by two identical wedge-shaped nylon keepers 48 fixed respectively on the bottom member 4 and the top member 5 of the surrounding frame 1. The two keepers 48 also serve to locate the panel 7 laterally by means of grooves 49 which accommodate one side of the mullion wall.

In the event that lateral movement of the panel 7 is desired, a laterally and leftwardly directed force exerted on the mullion will cause the mullion to move out of the two grooves 49. Recesses 50, FIG. 6, are cut in the outer side edge of the track 14 to accommodate cooperating wedge-shaped extrusions 50a on the roller housings 51 for the rollers 16 in the fully closed position of the panel 7. When opening pressure is exerted on the panel 7, the wedge-shaped extrusions 50a press against the recesses 50 and force the housing 51, together with the entire panel 7, to move outwards, thereby relieiving pressure on the sealing strip 31 and enabling the entire panel 7 to move freely. Lips 52, provided on the housings 51, prevent the panel 7 from being derailed from the track 14.

When the panel 7 is moved rightwardly to its closed position, the wedging actions of the face 46 of the stop 47 acting on the side member 11 and the keepers 48 acting on the mullion again, press the entire panel 7 inwardly until the mullion engages in the grooves 49 in the keepers 48 at the top and bottom to press the members ll, 12 and 13 against the sealing strip 31 of the surrounding frame 1.

The link arms 17 and 26 are preferably provided of stainless steel and other components of the sliding window, except where otherwise indicated, are preferably provided of aluminum.

Referring to FIGS. 7 and 8, a modification is shown wherein the stops 32, 33 of the embodiment of FIGS. 1 to 6 are replaced by stop brackets 32a, 33a secured to the side member 2 of the frame 1. The stop brackets 32a, 33a mount pins 43a which replace the stops 43 of the previous embodiment and the link arms 17a and 26a have their outer end portions shaped to form recesses 42a to engage the pins 43a. Operation is as in the previous embodiment, that is to say the lefthand roller housing 18 and the lefthand guide 25 abut the respective stop brackets 32a, 33a during the closing operation as the window approaches its closed position, thereby initiating inward pivoting movement of the panel 8. At

the end of the inward pivoting movement, the lefthand link arms 17a and 26a have the pins 43a engaged in their recesses 42a. When opening movement is initiated, the cooperating pins 43a and recesses 42a prevent rightward movement of the roller housings 18 and guides 25 until the panel 8 has pivoted outwardly on the link arms 17a, 26a into the plane of the outer track.

What is claimed is:

1. A sliding window comprising in combination a frame including compression sealing means, a slidable panel movable in said frame between a closed position and an open position, a further panel and mounting means, including pivot arms, for mounting said slidable panel in said frame, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, wherein said frame includes a lower member with a track thereon, said further panel includes a mullion with compression sealing means thereon, and said mounting means are so constructed that said slidable panel in open positions is movable in said further plane along said track but as said slidable panel approaches said closed position it is swung, on said pivot arms, into the plane of said further panel to bring it into abutment with said compression sealing means on said frame and said compression sealing means on said mullion of said further panel, wherein said mounting means include housings and rollers mounted in said housings and to run on said track, one end of each said pivot arms being pivotably secured to a respective one of said housings and the other end of each of said pivot arms being pivotably secured to said slidable panel, and wherein said housings and said rollers of said mounting means are provided at the lower end of said slidable panel and said mounting means further includes guides co-operating with a further track on an upper member of said frame, which said further track is mounted above and parallel to said track, said guides having one end of respective further pivot arms pivotably secured thereto and the other end of each of said further pivot arms being pivotably secured to the upper end of said slidable panel.

2. A sliding window as claimed in claim 1, wherein said mounting means include stops on said track and said further track, which stops are abutted respectively by one of said housings and one of said guides, as said slidable panel approaches said closed position during a closing movement, said stops being effective to prevent further movement of said one of said housings and said one of said guides, whereby further closing movement of said slidable panel causes said slidable panel to swing inwardly on said pivot arms into the plane of said further panel.

3. A sliding window as claimed in claim 1, including tie bars coupling said housings one to the other.

4. A sliding window as claimed in claim 1, including stop means to prevent sliding movement of said housings and said guides along said track and said further track respectively, on opening movement of said slidable panel from said closed position, until said slidable panel has moved into said further plane.

5. A sliding window comprising in combination a frame including compression sealing means, a slidable movable in said further plane along said track but as said slidable panel approaches said closed position it is swung, on said pivot arms, into the plane of said further panel to bring it into abutment with said compression sealing means on said frame and said compression sealing means on said mullion of said further panel, wherein said mounting means include housings and rollers mounted in said housings and to run on said track, one end of each of said pivot arms being pivotably secured to a respective one of said housings and the other end of each of said pivot arms being pivotably secured to said slidable panel, wherein said housings and said rollers of said mounting means are provided at the lower end of said slidable panel and said mounting means further includes guides co-operating with a fur ther track on an upper member of said frame, which said further track is mounted above and parallel to said track, said guides having one end of respective further pivot arms pivotably secured thereto and the other end of each of said further pivot arms being pivotably secured to the upper end of said slidable panel, including stop means to prevent sliding movement of said housings and said guides along said track'and said further track respectively, on opening movement of said slidable panel from said closed position, until said slidable panel has moved into said further plane, and wherein said stop means comprise stops secured on said frame and adapted to co-operate with end portions of said pivot arms and said further pivot arms, said end portions projecting beyond the positions of pivotal mounting of said pivot arms and said further pivot arms to said housings and said guides respectively.

6. A sliding window as claimed in claim 1, including additional means to urge said slidable panel against said compression sealing means, said additional means comprising a stop with an angled face on a side member of said frame which a side member at the leading edge of said slidable panel approaches as said slidable panel moves into said closed position, said angled face being effective to cam said side member at the leading edge of said slidable panel into engagement with said compressing sealing means on said frame.

7. A sliding window as claimed in claim 6, wherein said additional means further comprise a locking catch mounted on said frame at a position adjacent that at which a further side member at the trailing edge of said slidable panel lies as said slidable panel approaches said closed position, said locking catch co-operating with a panel movable in said frame between a closed position i and an open position, a further panel and mounting means, including pivot arms, for mounting said slidable panel in said frame, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, wherein said frame includes a lower member with a track thereon, said further panel includes a mullion with compression sealing means thereon, and said mounting means are so constructed that said slidable panel in open positions is keeper on said slidable panel such that actuation of said locking catch urges said slidable panel into a fully closed position and pulls said further side member of said slidable pane] into engagement with said compression sealing means on said mullion of said further panel.

8. A sliding window as claimed in claim 6, wherein said further panel is mounted on rollers to be slidable in said frame and co-operates with further additional means corresponding to said additional means provided for said slidable panel.

9. A sliding window as claimed in claim 8, wherein said further additional means further comprise wedge shaped keepers mounted on said frame and adapted to co-operate with said mullion of said further panel.

10. A sliding window as claimed. in claim 6, wherein said further panel is mounted on rollers to be slidable in said frame, and wherein said frame includes an additional track on which said rollers on which said further panel is mounted can roll, and said rollers on which said further panel is mounted are provided in additional housings, said additional track having recesses in the outer side cage thereof to co-operate with projections on said additional housings whereby, upon movement of said further panel from a closed position, said recesses co-operate with said projections to cam said further panel outwardly, thereby relieving pressure on said compression sealing means to permit easy sliding movement of said further panel.

11. A sliding window comprising, in combination: a frame including compression sealing means, a slidable panel movable on at least one track in said frame between a closed position and an open position, a further panel and mounting means, including pivot arms associating with at least one track for mounting said slidable panel in said frame through housings and rollers mounted in said housings, for moving in said at least one track, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, and wherein said mounting means include stops on at least one track which stops are abutted respectively by one of said housings, as said slidable panel approaches said closed position during a closing movement, said stops being effective to prevent further movement of said one of said housings, whereby further closing movement of said slidable panel causes said slidable panel to swing inwardly on said pivot arms into the plane of said further panel. 

1. A sliding window comprising in combination a frame including compression sealing means, a slidable panel movable in said frame between a closed position and an open position, a further panel and mounting means, including pivot arms, for mounting said slidable panel in said frame, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, wherein said frame includes a lower member with a track thereon, said further panel includes a mullion with compression sealing means thereon, and said mounting means are so constructed that said slidable panel in open positions is movable in said further plane along said track but as said slidable panel approaches said closed position it is swung, on said pivot arms, into the plane of said further panel to bring it into abutment with said compression sealing means on said frame and said compression sealing means on said mullion of said further panel, wherein said mounting means include housings and rollers mounted in said housings and to run on said track, one end of each said pivot arms being pivotably secured to a respective one of said housings and the other end of each of said pivot arms being pivotably secured to said slidable panel, and wherein said housings and said rollers of said mounting means are provided at the lower end of said slidable panel and said mounting means further includes guides co-operating with a further track on an upper member of said frame, which said further track is mounted above and parallel to said track, said guides having one end of respective further pivot arms pivotably secured thereto and the other end of each of said further pivot arms being pivotably secured to the upper end of said slidable panel.
 2. A sliding window as claimed in claim 1, wherein said mounting means include stops on said track and said further track, which stops are abutted respectively by one of said housings and one of said guides, as said slidable panel approaches said closed position during a closing movement, said stops being effective to prevent further movement of said one of said housings and said one of said guides, whereby further closing movement of said slidable panel causes said slidable panel to swing inwardly on said pivot arms into the plane of said further panel.
 3. A sliding window as claimed in claim 1, including tie bars coupling said housings one to the other.
 4. A sliding window as claimed in claim 1, including stop means to prevent sliding movement of said housings and said guides along said track and said further track respectively, on opening movement of said slidable panel from said closed position, until said slidable panel has moved into said further plane.
 5. A sliding window comprising in combination a frame including compression sealing means, a slidable panel movable in said frame between a closed position and an open position, a further panel and mounting means, including pivot arms, for mounting said slidable panel in said frame, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, wherein said frame includes a lower member with a track thereon, said further panel includes a mullion with compression sealing means thereon, and said mounting means are so constructed that said slidable panel in open positions is movable in said further plane along said track but as said slidable panel approaches said closed position it is swung, on said pivot arms, into the plane of said further panel to bring it into abutment with said compression sealing means on said frame and said compression sealing means on said mullion of said further panel, wherein said mounting means include housings and rollers mounted in said housings and to run on said track, one end of each of said pivot arms being pivotably secured to a respective one of said housings and the other end of each of said pivot arms being pivotably secured to said slidable panel, wherein said housings and said rollers of said mounting means are provided at the lower end of said slidable panel and said mounting means further includes guides co-operating with a further track on an upper member of said frame, which said further track is mounted above and parallel to said track, said guides having one end of respective further pivot arms pivotably secured thereto and the other end of each of said further pivot arms being pivotably secured to the upper end of said slidable panel, including stop means to prevent sliding movement of said housings and said guides along said track and said further track respectively, on opening movement of said slidable panel from said closed position, until said slidable panel has moved into said further plane, and wherein said stop means comprise stops secured on said frame and adapted to co-operate with end portions of said pivot arms and said further pivot arms, said end portions projecting beyond the positions of pivotal mounting of said pivot arms and said further pivot arms to saId housings and said guides respectively.
 6. A sliding window as claimed in claim 1, including additional means to urge said slidable panel against said compression sealing means, said additional means comprising a stop with an angled face on a side member of said frame which a side member at the leading edge of said slidable panel approaches as said slidable panel moves into said closed position, said angled face being effective to cam said side member at the leading edge of said slidable panel into engagement with said compressing sealing means on said frame.
 7. A sliding window as claimed in claim 6, wherein said additional means further comprise a locking catch mounted on said frame at a position adjacent that at which a further side member at the trailing edge of said slidable panel lies as said slidable panel approaches said closed position, said locking catch co-operating with a keeper on said slidable panel such that actuation of said locking catch urges said slidable panel into a fully closed position and pulls said further side member of said slidable panel into engagement with said compression sealing means on said mullion of said further panel.
 8. A sliding window as claimed in claim 6, wherein said further panel is mounted on rollers to be slidable in said frame and co-operates with further additional means corresponding to said additional means provided for said slidable panel.
 9. A sliding window as claimed in claim 8, wherein said further additional means further comprise wedge shaped keepers mounted on said frame and adapted to co-operate with said mullion of said further panel.
 10. A sliding window as claimed in claim 6, wherein said further panel is mounted on rollers to be slidable in said frame, and wherein said frame includes an additional track on which said rollers on which said further panel is mounted can roll, and said rollers on which said further panel is mounted are provided in additional housings, said additional track having recesses in the outer side cage thereof to co-operate with projections on said additional housings whereby, upon movement of said further panel from a closed position, said recesses co-operate with said projections to cam said further panel outwardly, thereby relieving pressure on said compression sealing means to permit easy sliding movement of said further panel.
 11. A sliding window comprising, in combination: a frame including compression sealing means, a slidable panel movable on at least one track in said frame between a closed position and an open position, a further panel and mounting means, including pivot arms associating with at least one track for mounting said slidable panel in said frame through housings and rollers mounted in said housings, for moving in said at least one track, said mounting means being so arranged and disposed that said slidable panel in said closed position lies substantially in the same plane as said further panel and in abutment with said compression sealing means of said frame and, when moved from said closed position to said open position, moves out of said plane to lie in a further plane parallel to said plane but spaced therefrom such that said sliding panel can be overlapped with said further panel, and wherein said mounting means include stops on at least one track which stops are abutted respectively by one of said housings, as said slidable panel approaches said closed position during a closing movement, said stops being effective to prevent further movement of said one of said housings, whereby further closing movement of said slidable panel causes said slidable panel to swing inwardly on said pivot arms into the plane of said further panel. 